linux-kernel - Re: [PATCH v7 21/26] rust: alloc: implement `contains` for `Flags`

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Message-ID: <20240928203126.0477cc08.gary@garyguo.net>
Date: Sat, 28 Sep 2024 20:31:26 +0100
From: Gary Guo <gary@...yguo.net>
To: Danilo Krummrich <dakr@...nel.org>
Cc: ojeda@...nel.org, alex.gaynor@...il.com, wedsonaf@...il.com,
 boqun.feng@...il.com, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me,
 a.hindborg@...sung.com, aliceryhl@...gle.com, akpm@...ux-foundation.org,
 daniel.almeida@...labora.com, faith.ekstrand@...labora.com,
 boris.brezillon@...labora.com, lina@...hilina.net, mcanal@...lia.com,
 zhiw@...dia.com, cjia@...dia.com, jhubbard@...dia.com, airlied@...hat.com,
 ajanulgu@...hat.com, lyude@...hat.com, linux-kernel@...r.kernel.org,
 rust-for-linux@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v7 21/26] rust: alloc: implement `contains` for `Flags`

On Thu, 12 Sep 2024 00:52:57 +0200
Danilo Krummrich <dakr@...nel.org> wrote:

> Provide a simple helper function to check whether given flags do
> contain one or multiple other flags.
> 
> This is used by a subsequent patch implementing the Cmalloc `Allocator`
> to check for __GFP_ZERO.
> 
> Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
> Reviewed-by: Benno Lossin <benno.lossin@...ton.me>
> Signed-off-by: Danilo Krummrich <dakr@...nel.org>

Reviewed-by: Gary Guo <gary@...yguo.net>

> ---
>  rust/kernel/alloc.rs | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index aabdf80e4f7b..caa0b9dfac87 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -34,7 +34,7 @@
>  /// They can be combined with the operators `|`, `&`, and `!`.
>  ///
>  /// Values can be used from the [`flags`] module.
> -#[derive(Clone, Copy)]
> +#[derive(Clone, Copy, PartialEq)]
>  pub struct Flags(u32);
>  
>  impl Flags {
> @@ -42,6 +42,11 @@ impl Flags {
>      pub(crate) fn as_raw(self) -> u32 {
>          self.0
>      }
> +
> +    /// Check whether `flags` is contained in `self`.
> +    pub fn contains(self, flags: Flags) -> bool {
> +        (self & flags) == flags
> +    }
>  }
>  
>  impl core::ops::BitOr for Flags {